Method of diagnosing, monitoring, and staging prostate cancer

ABSTRACT

The present invention provides a new method for detecting, diagnosing, monitoring, staging and prognosticating prostate cancer.

This application is national stage application of a 371 of PCT/US99/10548 filed on May 12, 1999, which claims benefit of 60/086,265 filedon May 21, 1998.

FIELD OF THE INVENTION

This invention relates, in part, to newly developed assays fordetecting, diagnosing, monitoring, staging, and prognosticating cancers,particularly prostate cancer.

BACKGROUND OF THE INVENTION

Cancer of the prostate is the most prevalent malignancy in adult males,excluding skin cancer, and is an increasingly prevalent health problemin the United States. In 1996, it was estimated that in the UnitedStates, 41,400 deaths would result from this disease, indicating thatprostate cancer is second only to lung cancer as the most common causeof death in the same population. If diagnosed and treated early, whenthe cancer is still confined to the prostate, the chance of cure issignificantly higher.

Treatment decisions for an individual are linked to the stage ofprostate cancer present in that individual. A common classification ofthe spread of prostate cancer was developed by the American UrologicalAssociation (AUA). The AUA classification divides prostate tumors intofour stages, A to D. Stage A, microscopic cancer within prostate, isfurther subdivided into stages A1 and A2. Sub-stage A1 is awell-differentiated cancer confined to one site within the prostate.Treatment is generally observation, radical prostatectomy, or radiation.Sub-stage A2 is a moderately to poorly differentiated cancer at multiplesites within the prostate. Treatment is radical prostatectomy orradiation. Stage B, palpable lump within the prostate, is furthersubdivided into stages B1 and B2. In sub-stage B1, the cancer forms asmall nodule in one lobe of the prostate. In sub-stage B2, the cancerforms large or multiple nodules, or occurs in both lobes of theprostate. Treatment for both sub-stages B1 and B2 is either radicalprostatectomy or radiation. Stage C is a large cancer mass involvingmost or all of the prostate and is further subdivided into two stages.In sub-stage C1, the cancer forms a continuous mass that may haveextended beyond the prostate. In sub-stage C2, the cancer forms acontinuous mass that invades the surrounding tissue. Treatment for boththese sub-stages is radiation with or without drugs. The fourth stage ismetastatic cancer and is also subdivided into two stages. In sub-stageD1, the cancer appears in the lymph nodes of the pelvis. In sub-stageD2, the cancer involves tissues beyond lymph nodes. Treatment for boththese sub-stages is systemic drugs to address the cancer as well aspain.

However, current prostate cancer staging methods are limited. As many as50% of prostate cancers initially staged as A2, B, or C are actuallystage D, metastatic. Discovery of metastasis is significant becausepatients with metastatic cancers have a poorer prognosis and requiresignificantly different therapy than those with localized cancers. Thefive year survival rates for patients with localized and metastaticprostate cancers are 93% and 29%, respectively.

Accordingly, there is a great need for increasingly sensitive methodsfor the staging of a cancer in a human to determine whether or not suchcancer has metastasized and for monitoring the progress of a cancer in ahuman.

In the present invention, methods are provided for detecting,diagnosing, monitoring, staging and prognosticating cancers,particularly prostate cancer via seven (7) Prostate Specific Genes(PSG). The seven PSGs refer, among other things, to native proteinsexpressed by the genes comprising the polynucleotide sequences of any ofSEQ ID NO: 1, 2, 3, 4, 5, 6, or 7. In the alternative, what is meant bythe seven PSGs as used herein, means the native mRNAs encoded by thegenes comprising any of the polynucleotide sequences of SEQ ID NO: 1, 2,3, 4, 5, 6 or 7 or levels of the genes comprising any of thepolynucleotide sequences of SEQ ID NO: 1, 2, 3, 4, 5, 6 or 7.

Other objects, features, advantages and aspects of the present inventionwill become apparent to those of skill in the art from the followingdescription. It should be understood, however, that the followingdescription and the specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only.Various changes and modifications within the spirit and scope of thedisclosed invention will become readily apparent to those skilled in theart from reading the following description and from reading the otherparts of the present disclosure.

SUMMARY OF THE INVENTION

Toward these ends, and others, it is an object of the present inventionto provide a method for diagnosing the presence of prostate cancer in apatient which comprises measuring levels of PSG in a sample of cells,tissue or bodily fluid from the patient and comparing the measuredlevels of PSG with levels of PSG in preferably the same cells, tissue,or bodily fluid type of a control, wherein an increase in the measuredPSG levels in the patient versus levels of PSG in the control isassociated with prostate cancer.

Another object of the present invention is to provide a method ofdiagnosing metastatic prostate cancer in a patient which comprisesmeasuring PSG levels in a sample of cells, tissue, or bodily fluid fromthe patient and comparing the measured PSG levels with levels of PSG inpreferably the same cells, tissue, or bodily fluid type of a control,wherein an increase in measured PSG levels in the patient versus levelsof PSG in the control is associated with a cancer which hasmetastasized.

Another object of the present invention is to provide a method ofstaging prostate cancer in a patient which comprises identifying apatient having prostate cancer, measuring levels of PSG in a sample ofcells, tissues, or bodily fluid obtained from the patient, and comparingthe measured PSG levels with levels of PSG in preferably the same cells,tissue or bodily fluid type of a control. An increase in measured PSGlevels in the patient versus PSG levels in the control can be associatedwith a cancer which is progressing while a decrease or equivalent levelof PSG measured in the patient versus the control can be associated witha cancer which is regressing or in remission.

Another object of the present invention is to provide a method ofmonitoring prostate cancer in a patient for the onset of metastasis. Themethod comprises identifying a patient having prostate cancer that isnot known to have metastasized, periodically measuring levels of PSG ina sample of cells, tissues, or bodily fluid obtained from the patient,and comparing the measured PSG levels with levels of PSG in preferablythe same cells, tissue, or bodily fluid type of a control, wherein anincrease in measured PSG levels versus control PSG levels is associatedwith a cancer which has metastasized.

Yet another object of the present invention is to provide a method ofmonitoring the change in stage of prostate cancer in a patient whichcomprises identifying a patient having prostate cancer, periodicallymeasuring levels of PSG in a sample of cells, tissue, or bodily fluidobtained from the patient, and comparing the measured PSG levels withlevels of PSG in preferably the same cells, tissues, or bodily fluidtype of a control wherein an increase in measured PSG levels versus thecontrol PSG levels is associated with a cancer which is progressing anda decrease in the measured PSG levels versus the control PSG levels isassociated with a cancer which is regressing or in remission.

Other objects, features, advantages and aspects of the present inventionwill become apparent to those of skill in the art from the followingdescription. It should be understood, however, that the followingdescription and the specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only.Various changes and modifications within the spirit and scope of thedisclosed invention will become readily apparent to those skilled in theart from reading the following description and from reading the otherparts of the present disclosure.

DESCRIPTION OF THE INVENTION

The present invention relates to diagnostic assays and methods, bothquantitative and qualitative for detecting, diagnosing, monitoring,staging, and prognosticating cancers by comparing levels of PSG measuredin a patient with levels of PSG in a control. What is meant by “levelsof PSG” as used herein, means levels of the native protein expressed bythe gene comprising the polynucleotide sequence of any of SEQ ID NO: 1,2, 3, 4, 5, 6 or 7. In the alternative, what is meant by “levels of PSG”as used herein, is levels of the native mRNA encoded by the genecomprising any of the polynucleotide sequence of SEQ ID NO: 1, 2, 3, 4,5, 6 or 7 or levels of the gene comprising any of the polynucleotidesequence of SEQ ID NO: 1, 2, 3, 4, 5, 6 or 7. Such levels are preferablymeasured in at least one of cells, tissues and/or bodily fluids, andincludes determination of both normal and abnormal levels of PSGs. Thus,for instance, a diagnostic assay in accordance with the invention fordiagnosing overexpression of PSG protein compared to control bodilyfluids, cells, or tissue samples may be used to diagnose the presence ofcancers, including prostate cancer. Any of the seven PSGs may bemeasured alone in the methods of the invention, all together or invarious combinations of the seven PSGs.

By “control” it is meant a human patient without cancer and/or noncancerous samples from the patient, also referred to herein as a normalhuman control; in the methods for diagnosing or monitoring formetastasis, control may also include samples from a human patient thatis determined by reliable methods to have prostate cancer which has notmetastasized.

All the methods of the present invention may optionally includemeasuring the levels of other cancer markers as well as PSG. Othercancer markers, in addition to PSG, useful in the present invention willdepend on the cancer being tested and are known to those of skill in theart. For example, simultaneous testing for increases in PSA as well asincreases in PSG are also within the scope of the present invention andbelieved to provide a higher level of assurance that such cancer beingtested is metastatic or the onset of metastasis has occurred.

Diagnostic Assays

The present invention provides methods -for diagnosing the presence ofprostate cancer by analyzing for changes in levels of PSG in cells,tissues or bodily fluids compared with levels of PSG in cells, tissuesor bodily fluids of preferably the same type from a normal humancontrol, wherein an increase in levels of PSG in the patient versus thenormal human control is associated with the presence of prostate cancer.Without limiting the instant invention, typically, for a quantitativediagnostic assay a positive result indicating the patient being testedhas cancer is one in which cells, tissues, or bodily fluid levels of thecancer marker, such as PSG, are at least two times higher, and mostpreferably are at least five times higher, than in preferably the samecells, tissues, or bodily fluid of a normal human control.

The present invention also provides a method of diagnosing metastaticprostate cancer in a patient having prostate cancer which has not yetmetastasized for the onset of metastasis. In the method of the presentinvention, a human cancer patient suspected of having prostate cancerwhich may have metastasized (but which was not previously known to havemetastasized) is identified. This is accomplished by a variety of meansknown to those of skill in the art. For example, in the case of prostatecancer, patients are typically diagnosed with prostate cancer followingtraditional detection methods.

In the present invention, determining the presence of PSG in cells,tissues, or bodily fluid, is particularly useful for discriminatingbetween prostate cancer which has not metastasized and prostate cancerwhich has metastasized.

Existing techniques have difficulty discriminating between prostatecancer which has metastasized and prostate cancer which has notmetastasized and proper treatment selection is often dependent upon suchknowledge.

In the present invention, the cancer marker levels measured in suchcells, tissue, or bodily fluid are PSGs, and are compared with levels ofPSG in preferably the same cells, tissue, or bodily fluid type of anormal human control. That is, if the cancer marker being observed isjust PSG in serum, this level is preferably compared with the level ofPSG in serum of a normal human patient. An increase in the PSG in thepatient versus the normal human control is associated with prostatecancer which has metastasized.

Without limiting the instant invention, typically, for a quantitativediagnostic assay a positive result indicating the cancer in the patientbeing tested or monitored has metastasized is one in which cells,tissues, or bodily fluid levels of the cancer marker, such as PSG, areat least two times higher, and most preferable are at least five timeshigher, than in preferably the same cells, tissues, or bodily fluid of anormal patient.

Staging

The invention also provides a method of staging prostate cancer in ahuman patient.

The method comprises identifying a human patient having such cancer andanalyzing a sample of cells, tissues, or bodily fluid from such patientfor PSG. Then, the method compares PSG levels in such cells, tissues, orbodily fluid with levels of PSG in preferably the same cells, tissues,or bodily fluid type of a normal human control sample, wherein anincrease in PSG levels in the patient versus the normal human control isassociated with a cancer which is progressing and a decrease in thelevels of PSG is associated with a cancer which is regressing or inremission.

Monitoring

Further provided is a method of monitoring prostate cancer in a humanhaving such cancer for the onset of metastasis. The method comprisesidentifying a human patient having such cancer that is not known to havemetastasized; periodically analyzing a sample of cells, tissues, orbodily fluid from such patient for PSG; and comparing the PSG levels insuch cells, tissue, or bodily fluid with levels of PSG in preferably thesame cells, tissues, or bodily fluid type of a normal human controlsample, wherein an increase in PSG levels in the patient versus thenormal human control is associated with a cancer which has metastasized.

Further provided by this invention is a method of monitoring the changein stage of prostate cancer in a human having such cancer. The methodcomprises identifying a human patient having such cancer; periodicallyanalyzing a sample of cells, tissue, or bodily fluid from such patientfor PSG; comparing the PSG levels in such cells, tissue, or bodily fluidwith levels of PSG in preferably the same patient.

Monitoring such patient for onset of metastasis is periodic andpreferably done on a quarterly basis. However, this may be more or lessfrequent depending on the cancer, the particular patient, and the stageof the cancer.

Assay Techniques

Assay techniques that can be used to determine levels of geneexpression, such as PSG of the present invention, in a sample derivedfrom a host are well-known to those of skill in the art. Such assaymethods include radioimmunoassays, reverse transcriptase PCR (RT-PCR)assays, immunohistochemistry assays, in situ hybridization assays,competitive-binding assays, Western Blot analyses and ELISA assays.Among these, ELISAs are frequently preferred to diagnose a gene'sexpressed protein in biological fluids. An ELISA assay initiallycomprises preparing an antibody, if not readily available from acommercial source, specific to PSG, preferably a monoclonal antibody. Inaddition a reporter antibody generally is prepared which bindsspecifically to PSG. The reporter antibody is attached to a detectablereagent such as radioactive, fluorescent or enzymatic reagent, forexample horseradish peroxidase enzyme or alkaline phosphatase.

To carry out the ELISA, antibody specific to PSG is incubated on a solidsupport, e.g., a polystyrene dish, that binds the antibody. Any freeprotein binding sites on the dish are then covered by incubating with anon-specific protein such as bovine serum albumin. Next, the sample tobe analyzed is incubated in the dish, during which time PSG binds to thespecific antibody attached to the polystyrene dish. Unbound sample iswashed out with buffer. A reporter antibody specifically directed to PSGand linked to horseradish peroxidase is placed in the dish resulting inbinding of the reporter antibody to any monoclonal antibody bound toPSG. Unattached reporter antibody is then washed out. Reagents forperoxidase activity, including a calorimetric substrate are then addedto the dish. Immobilized peroxidase, linked to PSG antibodies, producesa colored reaction product. The amount of color developed in a giventime period is proportional to the amount of PSG protein present in thesample. Quantitative results typically are obtained by reference to astandard curve.

A competition assay may be employed wherein antibodies specific to PSGattached to a solid support and labeled PSG and a sample derived fromthe host are passed over the solid support and the amount of labeldetected attached to the solid support can be correlated to a quantityof PSG in the sample.

Nucleic acid methods may be used to detect PSG mRNA as a marker forprostate cancer. Polymerase chain reaction (PCR) and other nucleic acidmethods, such as ligase chain reaction (LCR) and nucleic acid sequencebased amplification (NASABA), can be used to detect malignant cells fordiagnosis and monitoring of various malignancies. For example,reverse-transcriptase PCR (RT-PCR) is a powerful technique which can beused to detect the presence of a specific mRNA population in a complexmixture of thousands of other mRNA species. In RT-PCR, an mRNA speciesis first reverse transcribed to complementary DNA (cDNA) with use of theenzyme reverse transcriptase; the cDNA is then amplified as in astandard PCR reaction. RT-PCR can thus reveal by amplification thepresence of a single species of mRNA. Accordingly, if the mRNA is highlyspecific for the cell that produces it, RT-PCR can be used to identifythe presence of a specific type of cell.

Hybridization to clones or oligonucleotides arrayed on a solid support(i.e., gridding) can be used to both detect the expression of andquantitate the level of expression of that gene. In this approach, acDNA encoding the PSG gene is fixed to a substrate. The substrate may beof any suitable type including but not limited to glass, nitrocellulose,nylon or plastic. At least a portion of the DNA encoding the PSG gene isattached to the substrate and then incubated with the analyte, which maybe RNA or a complementary DNA (cDNA) copy of the RNA, isolated from thetissue of interest.

Hybridization between the substrate bound DNA and the analyte can bedetected and quantitated by several means including but not limited toradioactive labeling or fluorescence labeling of the analyte or asecondary molecule designed to detect the hybrid. Quantitation of thelevel of gene expression can be done by comparison of the intensity ofthe signal from the analyte compared with that determined from knownstandards. The standards can be obtained by in vitro transcription ofthe target gene, quantitating the yield, and then using that material togenerate a standard curve.

The above tests can be carried out on samples derived from a variety ofpatients' cells, bodily fluids and/or tissue extracts (homogenates orsolubilized tissue) such as from tissue biopsy and autopsy material.Bodily fluids useful in the present invention include blood, urine,saliva, or any other bodily secretion or derivative thereof. Blood caninclude whole blood, plasma, serum, or any derivative of blood.

EXAMPLES

The present invention is further described by the following examples.These examples are provided solely to illustrate the invention byreference to specific embodiments. These exemplifications, whileillustrating certain specific aspects of the invention, do not portraythe limitations or circumscribe the scope of the disclosed invention.

Example 1 PSGs

Searches were carried out and PSGs identified using the following SearchTools as part of the LIFESEQ® database available from IncytePharmaceuticals, Palo Alto, Calif.:

-   -   1. Library Comparison (compares one library to one other        library) allows the identification of clones expressed in tumor        and absent or expressed at a lower level in normal tissue.    -   2. Subsetting is similar to library comparison but allows the        identification of clones expressed in a pool of libraries and        absent or expressed at a lower level in a second pool of        libraries.    -   3. Transcript Imaging lists all of the clones in a single        library or a pool of libraries based on abundance. Individual        clones can then be examined using Electronic Northerns to        determine the tissue sources of their component ESTs.    -   4. Protein Function: Incyte has identified subsets of ESTs with        a potential protein function based on homologies to known        proteins, Some examples in this database include Transcription        Factors and Proteases. Some leads were identified by searching        in this database for clones whose component ESTs showed disease        specificity.

Electronic subtractions, transcript imaging and protein functionsearches were used to identify clones, whose component ESTs wereexclusively or more frequently found in libraries from specific tumors.Individual candidate clones were examined in detail by checking whereeach EST originated.

TABLE 1 SEQ ID Gene ID NO: Clone ID # # 1 1550426 244673 ProteinFunction (Transcription Factors) 2 1255804  14878 Subsetting 3 1808432255819 Subsetting 4 3930803 none Subsetting 5  645804 235032 Subsetting6 1862352 221558 Subsetting 7 1450626 236019 Subsetting

Example 2 Measurement of SEQ ID NO:1; Clone ID # 1550426; Gene ID#244673 (pro101)

The example is carried out using standard techniques, which are wellknown and routine to those of skill in the art, except where otherwisedescribed in detail. Routine molecular biology techniques of thefollowing example are carried out as described in standard laboratorymanuals, such as Sambrook et al., MOLECULAR CLONING: A LABORATORYMANUAL, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold SpringHarbor, N.Y. (1989).

Relative Quantitation of Gene Expression

Real-time quantitative PCR with fluorescent Taqman probes is aquantitative detection system utilizing the 5′-3′ nuclease activity ofTaq DNA polymerase. The method uses an internal fluorescentoligonucleotide probe (Taqman) labeled with a 5′ reporter dye and adownstream, 3′ quencher dye. During PCR, the 5′-3′ nuclease activity ofTaq DNA polymerase releases the reporter, whose fluorescence can then bedetected by the laser detector of the Model 7700 Sequence DetectionSystem (PE Applied Biosystems, Foster City, Calif., USA).

Amplification of an endogenous control is used to standardize the amountof sample RNA added to the reaction and normalize for ReverseTranscriptase (RT) efficiency. Either cyclophilin,glyceraldehyde-3-phosphate dehydrogenase (GAPDH) or 18S ribosomal RNA(rRNA) is used as this endogenous control. To calculate relativequantitation between all the samples'studied, the target RNA levels forone sample are used as the basis for comparative results (calibrator).Quantitation relative to the “calibrator” is obtained using the standardcurve method or the comparative method (User Bulletin #2: ABI PRISM 7700Sequence Detection System).

To evaluate the tissue distribution, and the level of pro101 (SEQ IDNO:1) in normal and tumor tissue, total RNA was extracted from tumor andmatched normal adjacent tissues and from unmatched tumor and normaltissues. Subsequently, first strand cDNA was prepared with reversetranscriptase and the polymerase chain reaction carried out usingprimers and Taqman probe specific to pro101 (SEQ ID NO:1). The resultswere obtained using the ABI PRISM 7700 Sequence Detector. The absolutenumbers are relative levels of expression of pro101 (SEQ ID NO:1)compared to the calibrator.

The absolute numbers are depicted in the following Table 2 as relativelevels of expression in 12 normal tissues of pro101 (SEQ ID NO:1)compared to kidney (calibrator). These RNA samples were generated bypooling samples from a particular tissue from different individuals.

TABLE 2 Relative levels of pro101 Expression in Pooled Samples TissueNORMAL Brain 1.2 Heart 2 Kidney 1 Liver 7.2 Lung 48.2 Mammary 2.5Prostate 1418.4 Spleen 1.6 Small 1.9 Testis 57.3 Thymus 1.3 Uterus 7.6

The relative levels of expression in Table 2 show that for the PSGpro101 (SEQ ID NO:1) mRNA expression is more than 20 fold higher in thepool of normal prostate compared with the other 11 normal tissue poolsanalyzed. These results demonstrate that mRNA expression of the PSG ishighly specific for prostate.

The tissues shown in Table 2 correspond to pools of samples fromdifferent individuals. The tissues shown in the following Table 3 wereobtained from individuals and are not pooled. Hence the values for mRNAexpression levels shown in Table 2 cannot be directly compared to thevalues shown in Table 3.

The absolute numbers in Table 3 are relative levels of expression ofpro101 (SEQ ID NO:1) compared to kidney (calibrator), in 60 pairs ofmatching samples. Each matching pair contains the cancer sample for aparticular tissue and the normal adjacent sample for that same tissue,from the same individual. The results from 3 unmatched ovary tumor, 3unmatched normal ovary, 1 unmatched mammary tumor and 1 unmatched normalmammary gland are also shown.

TABLE 3 Relative Levels of pro101 Expression in Individual SamplesTISSUE CANCER MATCHING UNMATCHED Prostate 1 103.9 0 Prostate 2 2219 84.2Prostate 3 5048.2 3623.6 Prostate 4 11052.3 2029.4 Prostate 5 229.1 41.1Prostate 6 57.9 25.3 Prostate 7 58.5 57.069 Prostate 8 1074.6 610.8Prostate 9 32.7 79.3 Prostate 10 15.8 2.09 Prostate 11 436.4 438Prostate 12 49.5 59.3 Prostate 13 128 56 Bladder 1 0 0 Bladder 2 0 0Bladder 3 0.7 0 Colon 1 0 0 Colon 2 0 0 Colon 3 0 0 Colon 4 3.3 1.9Colon 5 0.1 0.8 Colon 6 0 0 Lung 1 0 0 Lung 2 0.5 1.6 Lung 3 1.4 2.1Lung 4 0 0 Lung 5 0 0 Kidney 1 0 0 Kidney 2 0 0 Kidney 3 0 0 Kidney 4 00 Liver 1 1.5 5.7 Liver 2 26.9 7.9 Liver 3 0 0 Pancreas 1 0.9 0.9Pancreas 2 3 0 Pancreas 3 0 0 Pancreas 4 0 0 Pancreas 5 0 0 Stomach 1 00 Stomach 2 0 0 Stomach 3 0 0 Stomach 4 0 0 Stomach 5 0 0 Sm Int 1 0 0Sm Int 2 0 0 Testis 1 0 0 Mammary 1 4 0 Mammary 2 5.6 0 Mammary 3 0.5 0Mammary 4 0.4 0 Mammary 5 0.5 Mammary 6 0 Endo 1 1.6 7.6 Endo 2 0 0 Endo3 0 0 Endo 4 0.3 0.2 Endo 5 5.8 5 Uterus 1 0 0 Uterus 2 0 0 Uterus 3 0 0Uterus 4 2.2 2.6 Ovary 1 1.4 Ovary 2 11.6 Ovary 3 1.5 Ovary 4 22.9 Ovary5 0 Ovary 6 1.8Among 128 samples in Table 3 representing 14 different tissues, thehigher levels of expression are consistently in prostate tissues. Theseresults confirm the tissue specificity results obtained with normalsamples shown in Table 2. Table 2 and Table 3 represent a combined totalof 140 samples in 18 human tissue types. Sixty-eight samplesrepresenting 13 different tissue types excluding prostate had nodetected pro101 mRNA (Table 3). In 4 tissues (stomach small intestinekidney and testis) no pro101 (SEQ ID NO:1) mRNA was detected for anysample tested from individuals (Table 3). Expression of this PSG wasdetected in testis in the pooled normal sample (Table 3). The medianexpression in prostate cancer samples in Table 3 is 166.5 units.Excluding vary 4 (Normal), only 1 sample in Table 3, Liver 2 (Cancer),is greater than 10% of this value.

Comparisons of the level of mRNA expression in prostate tumor samplesand the normal adjacent tissue from the same individuals are also shownin Table 3. The PSG pro101 (SEQ ID NO:1) is expressed at higher levelsin 9 of 13 (69%) prostate cancer tissues (Prostate 1, 2, 3, 4, 5, 6, 8,10 and 13) compared with the corresponding normal adjacent tissue. Thelevel of expression of this PSG is lower in prostate tumor compared tonormal adjacent tissue in two samples (Prostate 9 and 12). Equivalentlevels of expression were detected in two matched samples (Prostate 7and 11). Previous mRNA expression analysis for genes coding for thediagnostic markers PSA and PLA2 showed higher expression of the mRNA in40% to 80% of the tumor samples compared to matching normal adjacenttissue. Higher expression in the tumor sample compared to thecorresponding normal adjacent tissue is observed for Bladder 3, Colon 4,Liver 2, Pancreas 2, Endometrium 5 and. Mammary 1, 2 and 3. Higherexpression in the normal adjacent samples is observed for Colon 5, Lung2, Lung 3, Liver 1, Endometrium 1 and Uterus 4. However, the levelsdetected are in most cases comparable amongst the different tissues andlow compared to levels found in most prostate tissues.

The high level of tissue specificity, plus the mRNA overexpression in 9of 13 of the prostate tumor samples tested compared to the normaladjacent tissues are believed to make the PSG, pro101 (SEQ ID NO:1) agood diagnostic marker for detection of prostate cancer using mRNA.

1. A method for detecting the presence of prostate cancer in a patientcomprising: (a) measuring the level of PSG in a sample of prostate cellsor prostate tissue or blood, plasma, serum or urine obtained from thepatient; and (b) comparing the measured level of PSG with the level ofPSG in a sample of prostate cells or prostate tissue or blood, plasma,serum or urine obtained from a normal control, wherein an increase inthe measured level of PSG in the patient versus the PSG level in thenormal control is indicative of the presence of prostate cancer andwherein the PSG comprises SEQ ID NO:1.